test: fix test-http-content-length
test: fix test-http-content-length

Previously the test did not allow the last request to complete.

Fixes: https://github.com/iojs/io.js/pull/1137
PR-URL: https://github.com/iojs/io.js/pull/1145
Reviewed-By: Brian White <d8bbf19083844493ef08581d1c38fbc50ba5d18b@mscdex.net>
Reviewed-By: Bert Belder <9f2ff180696da386c1be31b4507155616db25dc6@gmail.com>

dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node